Dual purpose electrical contact element



Dec. 7, 1965 w. F. JUPTNER DUAL PURPOSE ELECTRICAL CONTACT ELEMENT FiledMay 29, 1963 FIGI INVENTOR.

F.' JUPTNER WILLIAM ATTORNEY United States Patent 3,222,487 DUAL PURPOSEELECTRICAL CONTACT ELEMENT William F. .luptner, Laguna Beach, Calif,assignor to Babcock Electronics Corporation, Costa Mesa, Califi, a

corporation of California Filed May 29, 1963, Ser. No. 284,066 5 Claims.(Cl. 200166) This invention relates generally to electrical contacts,and more particularly to electrical contacts for controlling differentamounts of electrical energy.

As is well known in the art, electrical contacts for controlling theflow of electrical current must be particularized to the amount ofcurrent to be controlled. That is, although electrical energy consistsof the flow of electrons along a given path, the number of electronswhich flow past a given point during a given unit of time may varyconsiderably. The electrical potential or voltage of the source of powercausing the flow of electrons may be substantially any value, and thecurrent or rate of electron flow will vary accordingly. As such, thegreater the voltage of the source, the higher the current for a givenset of circuit parameters.

The characteristics of a given electrical circuit also may varyconsiderably. That is, the resistance, inductance and capacitance of acircuit may be Within relatively wide ranges of values. The greater theresistance to the flow of electrons in the circuit, the smaller will bethe current. Thus, the current in a given circuit varies inversely withthe resistance of such circuit to the flow of electrons.

It has been discovered that an entirely different style or type ofelectrical contact is required for effectively controlling a smallamount of current as compared to contacts necessary for controllinglarge or heavy current. The distinction is founded principally on thefact that in controlling a large current considerable energy isavailable for overcoming the many obstacles or practical limitations toefiiciently operate a pair of contacts. Conversely, where only a smallamount of current is to be controlled, insufiicient electrical energy isavailable so that external energy must be supplied to overcome suchobstacles.

Electrical contacts are very vulnerable to the accumulation of foreignmaterials including moisture and films of various kinds which are theresult of atmospheric conditions. Where large current is available, suchforeign material and films are burned away by the current to therebyprovide good electrical conductivity between the pair of cooperatingcontacts. However, where only a minimum amount of current is to becontrolled, such foreign material and films create such a highresistance to the flow of electrons that the extremely weak current isvirtually stopped.

Heretofore, separate pairs of contacts frequently have been usedinterchangeably in a given switch or relay in accordance with the amountof current to be controlled. This, of course, has been inconvenient, andtime-consuming particularly where a given switch or relay has manydifferent applications. Also, in mass-producing such devices, it isdesirable to construct them with a given set of contacts which can beused for controlling any amount of current to be encountered.

It is an object of the present invention to provide an electricalcontact which is operable for efficiently con trolling widely differingamounts of electrical current.

Another object of the present invention is to provide an electricalcontact having a plurality of contact surfaces, the proper one of whichis substantially automatically selected in accordance with the amount ofcurrent to be controlled.

3,222,487 Patented Dec. 7, 1965 Another object of the present inventionis to provide a multipurpose electrical contact having both a relativelylarge contact surface and a relatively small contact surface, the formerof which is useable for controlling high current flow while the latteris useable for controlling small current flow.

A further object of the present invention is to provide an electricalcontact as characterized above wherein the relatively small contactsurface is automatically eliminated when large current is to becontrolled.

A still further object of the present invention is to provide anelectrical contact as characterized above wherein the relatively smallcontact surface is eroded away by controlling the large current flow soas to expose the relatively large contact surface.

A further object of the present invention is to provide a pair ofelectrical contacts of the multipurpose type having several differentsets of cooperating contact surfaces.

A further object of the present invention is to provide electricalcontacts as characterized above which are simple and inexpensive tomanufacture, and which are rugged and dependable in operation.

The novel features which I consider characteristic of my invention areset forth with particularity in the appended claims. The device itself,however, both as to its organization and mode of operation, togetherwith additional objects and advantages thereof, will best be understoddfrom the following description of specific embodiments when read inconnection with the accompanying drawings, in which:

FIGURE 1 is a side elevational view of an electrical contact accordingto the present invention;

FIGURE 2 is an end elevational view taken substantially along line 2-2of FIGURE 1;

FIGURE 3 is a fragmentary side elevational view of a portion of thecontact of FIGURE 1;

FIGURE 4 is a side elevational view of a pair of cooperating electricalcontacts according to the present invention;

FIGURE 5 is a side elevational view similar to FIG- URE 4, showing thecontacts in operating position; and

FIGURE 6 is an enlarged fragmentary sectional view of the cooperatingcontacts of FIGURE 5.

Like reference characters indicate corresponding parts throughout theseveral views of the drawings.

Referring to FIGURE 1 of the drawings, the embodi-' ment 8 chosen forillustration of the present invention comprises a generally U-shapedelongated body portion 10 formed of resilient material which is a goodconductor of electrical energy. One end 10a thereof is reversely bent toprovide mounting means in the form of a loop 12 to be positioned on aterminal post or the like as will hereinafter be explained.

The other end 1011 of body portion 10 is formed with an offset portion14 having a relatively large flat contact surface 14a. The offset natureof portion 14 removes surface 14a from the plane of end portion 10b asshown in FIGURES l, 4 and 5 of the drawings. This, as will hereinafterbecome more apparent, clearly defines the size and shape of the contactsurface 141:.

As shown most clearly in FIGURE 2 of the drawings, the body portion 10is of substantially constant width from the end portion 10a thereofthrough the relatively large contact surface 14a- Imrnediately adjacentthe contact surface 14a, or positioned on such surface if desired, is arelatively small contact surface 16 afforded by a tapered member 18. Inthe embodiment chosen for illustration of the present invention, thetapered member 18 is the extreme end of the body portion 10. However, aswill hereinafter become more apparent, such member 18 may be provided ina different position relative to'the large contact surface 14a.

The tapered member 18 extends beyond the plane of the contact surface14a, the apex of such tapered member lying in a plane which issubstantially parallel to the plane of surface 14a. As will be readilyapparent to those persons skilled in the art, the small contact surface16 may be formed of one or more comically-shaped extensions if desired.

The end portion 10b of body portion 10 is tapered as at 20 and 22 sothat the tapered member 18 is considerably smaller in width than themain portion of body portion 10. As such, the small contact surface 16is of limited length, such arrangement further reducing the'size of suchsurface.

Asshown most clearly in'FIGURE 1 of the drawings, the tapered member 18may be provided by upsetting the extreme end of the end portion 10b.That is, as will be readily apparent to those persons skilled in theart, the entire contact element may be formed in a forming press. Theforming die used in such press may include means for causing the'end ofend portion 10b to be upset as shown in FIGURES 1 and 2' to provide'thetapered member 18.

As shown most clearly in FIGURES 4 and 5, the mounting-loop 12 ispositioned about a mounting post 22, the latter of which is a terminalmember having good electrical conductivity. The loop 12 provides arelatively firm mechanical connection between the contact element andthe mounting post' 22. To assist such mechanical connection and toprovide good electrical conductivity therebetween, a bead of solder 24is provided within the V-shaped opening between loop 12 and post 22.Such solder may be poured into the opening so as to electrically bondthe variouselements together.

For cooperation with contact element 10 there is provided, as shown inFIGURES 4, 5 and 6, a contact member 26 which may take substantially anydesired form and shape. As shown therein, member 26 has a flat contactsurface-26a for engagement with both the small contact surface 16 andthe large contact surface 14a of contact element 8;

As will be readily apparent to those persons skilled in' the art,:thecontact member 26 is mounted for movement into and out of engagementwith contact element 8. In the alternative, contact member 26 may bestationary and the mounting post 22 movable with respect thereto formovement of contact element 8 in to engagement with contact surface 26a.The arrangement shown in the drawings is for illustration of the presentinvention and contemplates that the mounting post 22 is stationary andthat the contact member 26 is movable with respect thereto.

As mentioned above, the foreign materials, including moisture and otherfilms, which accumulate on the contact surfaces as a result of theatmosphere, are easily eliminated when high current electrical energy isbeing controlled. Such high current energy quickly traverses the gapcreated between the'contacts by the foreign material. Such arcingproduces considerable heat energy which quickly burns away the foreignmaterial and films to provide two clean contact surfaces on the contactelement and member.

When an extremely small amount of electrical current is beingcontrolled, insuificient energy is available from the current itself tocause arcing between the contact surfaces. If such arcing should takeplace, the small current is insufficient to provide heat for burningaway the foreign material.

Due to this shortcoming, the film and foreign material must be overcomeby external forces. To accomplish this with the small inherent biasingforce of the resilient body portion 10 of contact element 8, the area ofengagement between the contact element 8 and the contact member 26 mustbe extremely small. The reduced area causes the force of the bias tocreate a relatively high pressure between the contact element and thecontact member.

Such relatively high pressure is then utilized to physically breakthrough the foreign material and films so as to permit the contactsurfaces to be in firm engagement.

Due to the tapered construction of member 18 of the contact element 8,the contact surface 16 is virtually a single line. That is, due to thefact that the contact surface 26a of contact member 26 is relativelyfiat surface, the contact surface 16 which extends beyond the largecontact surface 14a engages the surface 26a along. a single line. Aswill be readily apparent to those persons skilled in the art, thisconfiguration provides a very small area of contact between the contactelement 8 and the contact member 26. The fact that the tapered member 18is of reduced width as compared to the width of body portion 10, thelength of the line of contact is reduced accordingly.

As a result of the'iaforedesonibed construction, the inherent biasingforce of contact element 8 is sufficient to cause the tapered member 18to be forced through the foreign material and films interposed betweenthe contact member 26 and contact element 8. This results in a lowresistance electrical circuit between contact member 26 and mountingpost 22 so that a small or weak current can be effectively controlled.The contact member 26 is permitted to be moved between circuit-makingand circuit-breaking positions relative to contact element 8 for controlof such low current electrical energy.

In the event the aforedescribeld contact arrangement is used to controlrelatively high current, it is not necessary for an operator to make anyinstallation changes. Rather, the contact element 8 is automaticallyconverted from a low current contact to a high current contact. Thisoccurs in substantially the following manner.

With the relatively small contact surface 16 making good electricalcontact with contact surface 260 of member 26, current is caused to flowbetween the element 8 and member 26. If such current is relatively high,the small area of contact between the contact surfaces offers arelatively high resistance. Upon opening and closing of the contacts,the large current produces arcing which generates a considerable amountof heat. Due to the tapered configuration of member 18, the apex thereofis most vulnerable to attack by such heat. As a result, the high heatenergy quickly erodes away the extended portion of the tapered member18, as shown most clearly in FIGURE 6 of the drawings.

When this occurs, the flat contact surface 26a of contact member 26engages the relatively large contact surface 14a of contact element 8.Such transition from low current use to high current use is indicatedwith broken lines in FIGURE 4. The inherent bias of resilient bodyportion 10 continues to urge the large contact surface 14a intoengagement with surface 26a of contact member 26.

The foreign material between the large contact surface 14a and contactsurface 26w are quickly burned away by the relatively large amount ofelectrical energy available. Initially, such foreign material preventsthe surfaces 14a and 26a from coming into firm engagement. As a result,the electrical resistance between such surfaces is relatively high. Thelarge current flow, however, traverses such high resistance therebyproducing considerable heat energy which quickly burns away the foreignmaterial. Thus, the contact surfaces 14a and 26a are permitted to moveinto firm engagement under the influence of the biasing force of contactelement 8. Thereafter, the contact member 26 may be moved between itscircuit-making and circuit-breaking position relative to contact element8 for control of the relatively high or strong current.

It is contemplated within the scope of the present invention thatexternal biasing means may be employed in place of the inherent biasingforce of the U-shaped contact element 8. In any event, however, thebiasing force urging the various contact surfaces to engagement may beconstant for control of either the low or high current electricalenergy.

It is thus seen that the present invention provides a multipurposeelectrical contact for controlling both low and high current electricalenergy. Further such contact is operable to substantially automaticallyconvert itself from condition for controlling low current energy tocondition for controlling high current energy.

Although I have shown and described certain specific embodiments of myinvention, I am fully aware that many modifications thereof arepossible. My invention, therefore, is not to be restricted exceptinsofar as is necessitated by the prior art and by the spirit of theappended claims.

I claim:

1. A dual purpose electrical contact element for use in efiicientlymaking and breaking either high or low current electrical energycomprising in combination, a contactor, a relatively large contact onsaid contactor for engagement with an electrically conductive member toefiiciently conduct therebetween electrical energy of predetermined highcurrent, and a relatively small contact on said contactor offset fromsaid large contact to normally engage said member and thereby preventengagement of said member by said relatively large contact, said smallcontact being sufliciently smaller than said large contact to beconsumed by heat upon conduction therethrough of said predetermined highcurrent energy, whereby said small contact is operable to conduct lowcurrent energy and said large contact is operable to conduct highcurrent energy with said member.

2. A dual purpose electrical contact element for use in eflicientlymaking and breaking either high or low current electrical energyaccording to claim 12 wherein said relatively large contact and saidrelatively small contact are contiguously formed on said contactor,whereby said contacts are caused to engage substantially adjacentportions of said electrically conductive member.

3. A dual purpose electrical contact element for use in efiicientlymaking and breaking either high or low current electrical energycomprising in combination, an elongated arcuate contactor formed ofresilient material one end of which is attached to an electricallyconductive mounting member, a relatively large contact mounted on saidcontactor at the other end thereof for engagement with an electricallyconductive member to conduct therebetween electrical energy ofpredetermined high current, the resiliency of said contactor providingthe contact force urging said large contact toward engagement with saidelectrically conductive member, and a relatively small contact on saidcontactor at said other end thereof oifset from said large contact tonormally engage said member due to the resiliency of said contactorurges said small contact into engagement with said member to conduct lowcurrent energy therebetween and urges said large contact into engagementtherewith upon consumption of said smaller contact to conduct highcurrent energy with said member.

4. A dual purpose electrical contact element for use in efiicientlymaking and breaking either high or low current electrical energycomprising in combination, a contactor, a relatively large contact onsaid contactor having a large contact surface for engagement with anelectrically conductive member to efficiently conduct therebetweenelectrical energy of predetermined high current, and a relatively smallcontact on said contactor adjacent said large contact and offsettherefrom to normally engage said member and thereby prevent engagementof said large contact therewith, said small contact having a relativelysmall contact surface sufliciently smaller than said large contactsurface to cause said small contact to be consumed by heat generated byconduction of said predetermined high current energy between said smallcontact and said electrically conductive member to thereby permit saidlarge contact to engage said electrically conductive member, wherebysaid small contact is operable to conduct low current energy and saidlarge contact to conduct said high current energy with said member.

5. A dual purpose electrical contact element for use in eflicientlymaking and breaking either high or low current electrical energycomprising in combination, an elongated arcuate contactor formed ofresilient material one end of which is attached to an electricallyconductive mounting member, a relatively large contact on said contactorat the other end thereof having a large contact surface for engagementwith an electrically conductive member to efficiently conducttherebetween electrical energy of predetermined high current, and arelatively small contact on said contactor at said other end thereofadjacent to said large contact and offset therefrom to engage saidmember under the influence of said resilient contactor to therebyprevent engagement of said large contact with said member, said smallcontact having a small contact surface sufficiently smaller than saidlarge contact surface to cause said small contact to be consumed by heatgenerated by conduction of said predetermined high current energybetween said small contact and said electrically conductive member tothereby permit said resilient contactor to cause said large contact toengage said electrically conductive member, whereby said resilientcontactor firstly causes said small contact to engage said electricallyconductive member and thereafter said large contact to engage saidmember after said small contact is consumed by heat of saidpredetermined high current energy therethrough.

References Cited by the Examiner UNITED STATES PATENTS 2,528,086 10/1950Schenck 200-166 3,180,961 4/1965 Waldorf 200-166 KATHLEEN H. CLAFFY,Primary Examiner.

BERNARD A. GILHEANY, HERMAN O. JONES,

Assistant Examiners.

1. A DUAL PURPOSE ELECTRICAL CONTACT ELEMENT FOR USE IN EFFICIENTLYMAKING AND BREAKING EITHER HIGH OR LOW CURRENT ELECTRICAL ENERGYCOMPRISING IN COMBINATION, A CONTACTOR, A RELATIVELY LARGE CONTACT ONSAID CONTACTOR FOR ENGAGEMENT WITH AN ELECTRICALLY CONDUCTIVE MEMBER TOEFFECIENTLY CONDUCT THEREBETWEEN ELECTRICAL ENERGY OF PREDETERMINED HIGHCURRENT, AND A RELATIVELY SMALL CONTACT ON SAID CONTACTOR OFFSET FROMSAID LARGE CONTACT TO NORMALLY ENGAGE SAID MEMBER AND THEREBY PREVENTENGAGEMENT OF SAID MEMBER BY SAID RELATIVELY LARGE CONTACT, SAID SMALLCONTACT BEING SUFFICIENTLY SMALLER THAN SAID LARGER CONTACT TO BECONSUMED BY HEAT UPON CONDUCTION THERETHROUGH OF SAID PREDETERMINED HIGHCURRENT ENERGY, WHEREBY SAID SMALL CONTACT IS OPERABLE TO CONDUCT LOWCURRENT ENERGY AND SAID LARGE CONTACT IS OPERABLE TO CONDUCT HIGHCURRENT ENERGY WITH SAID MEMBER.